Understanding Reinforced Autoclaved Aerated Concrete (RAAC) 

Reinforced Autoclaved Aerated Concrete (RAAC) is a lightweight concrete material prominently utilised in construction from the 1950s to the mid-1990s. Its primary applications included the formation of lightweight structural units like roof planks, wall/floor panels, and lightweight masonry blocks. It is worth highlighting that some buildings constructed during this period may contain components made of RAAC. Given recent developments regarding school closures, concerns regarding the integrity of buildings are certainly warranted. 

Appraising the lifespan of RAAC 

Originally designed with an approximate lifespan of 30 years, most RAAC elements in buildings have now exceeded this. RAAC is also susceptible to structural compromise upon exposure to moisture due to its aerated composition, allowing moisture infiltration and subsequent degradation. As it was typically deployed within structural elements such as planks constituting intermediate floors or roofs, RAAC components are often concealed beneath ceilings or other internal finishes. 

Conducting a thorough assessment 

For those overseeing properties where RAAC may have been used, a comprehensive audit to ascertain its presence is required. A good first step is to review the historical construction documents associated with the building. It may be worth contacting the local authority for documentation if records are incomplete. However, it’s important to exercise caution, as the actual construction might deviate from the depictions in the architectural drawings. 

Pursuing in-depth investigation 

If there is a suspicion regarding the presence of RAAC within a church premises, engaging a qualified surveyor for a comprehensive investigation and confirmation is advisable. Given the time frame during which RAAC products were utilised, proximity to asbestos-containing materials such as ceiling void boarding is possible. Churches should make their asbestos survey and management plans available to any surveyors or contractors carrying out investigations. If the church does not have an asbestos survey and management plan in place, it would be prudent for one to be carried out by a qualified surveyor alongside any investigations. Should RAAC be suspected, the surveyor may need to remove parts of the building to gain access to the RAAC and check its condition. It is important to note that any subsequent recommendations made by the surveyor will need to be followed.  

Find a surveyor  

A list of suitable surveyors can be found on the RICS website.  

More information 

More detailed information about RAAC can be found on the RICS website RICS website or UK Government website